This invention relates generally to aluminoxane compositions and more specifically to stable, liquid clathrate aluminoxane compositions obtained by the reaction in aromatic solvents of aluminoxanes, especially methylaluminoxane, with organic or inorganic compounds, especially salts which can dissociate or partially dissociate into cationic and anionic species (M-X species). In another aspect, the invention relates to insoluble solid aluminoxane-MX salt compositions. Furthermore, the invention relates to polymerization catalyst compositions which could optionally be supported on inert solid carriers.
Aluminoxanes are generally prepared by the hydrolysis of aluminum alkyls either by direct water addition or by treatment with salt hydrates. Aluminoxanes are used in combination with various types of metallocenes and/or transition metal compounds to catalyze olefin oligomerization and polymerization. These catalyst components can be supported on solid carriers such as metal oxides, for example silica or alumina, for use in heterogeneous and gas phase polymerizations.
Methylaluminoxane (MAO) is the most useful of all aluminoxanes for polymerization applications. However, certain limitations are associated with regular methylaluminoxane solutions. Such limitations include poor solubility, especially in aliphatic solvents, instability, and gel formation.
The present invention relates to the alleviation of most if not all of the present problems associated with the industrial use of methylaluminoxanes as co-catalyst components.
A co-pending U.S. Pat. application, Ser. No. 08/452,170, filed May 26, 1995, now U.S. Pat. No. 5,565,395, issued Oct. 15, 1996, describes the formation of aluminoxanate compositions which are the reaction products of aluminoxanes, such as methylaluminoxane, and certain salts of polyoxy-compounds such as sodium aluminate and lithium silicate. These materials are obtained by the formation of only a transient liquid clathrate which quickly turns to solid aluminoxane compositions described as aluminoxanates. My co-pending U.S. Pat. application, Ser. No. 08/508,005, filed Jul. 27, 1995, now U.S. Pat. No. 5,731,253, issued Mar. 24, 1998, describes siloxy-aluminoxane compositions which contain hydrocarbylsiloxane moieties which are substantially free of Si--OH bonds, in which the molar portion of aluminum to hydrocarbylsiloxane is from about 1:1 to 1000:1.